Photographic color papers (also known as color print materials) are generally processed in a series of processing steps which includes color developing, bleach-fixing and rinsing. The bleach-fix bath typically contains a thiosulfate-containing compound which functions as a fixing agent and forms a water-soluble silver thiosulfate complex. Following the bleach-fix step, the resulting photographic prints are treated with a rinse solution to remove unwanted thiosulfate complex and other unwanted residues of the prior processing steps. Those prints are then conveyed through a dryer where they are contacted with warm dry air.
Many different formulations have been proposed for use as a rinse solution in such processes. Generally, the rinse solution includes a biocide to control unwanted biological growth. It may also contain any of a variety of sequestering agents to retain calcium ion in solution, thereby avoiding precipitation of calcium salts which can foul processing apparatus and become deposited on the prints.
One potential problem in such processing methods is the precipitation of elemental sulfur or silver sulfide from the decomposition of silver thiosulfate complex generated in the bleach-fix step. Such precipitates are also highly undesirable.
It is also known to include in rinse solutions a vinyl pyrrolidone polymer, as described for example in U.S. Pat. No. 4,537,856 and Japanese Patent Publication 28945/86. These polymers are effective to reduce precipitation of elemental sulfur and silver sulfide. When such polymers are used alone, the surfaces of the photographic prints become tacky and can cause jamming in processing apparatus and dryers. This problem has been solved in part by incorporating a polysiloxane surfactant into the rinse solution, as described in WO 91/05289 (published Apr. 18, 1991).
While the problem with jamming has been solved to a considerable extent with the polysiloxane surfactant, it has been observed that the prints may still become tacky and materials can leach out of them and become deposited on transport rollers in the dryer section of the processing equipment. Thus, consistency in solving the noted problems has not always been achieved with the known rinse solutions. In addition, the polysiloxane surfactant is considered to be expensive and its replacement would be desirable.
Thus, there is a need to provide a process whereby prints can be subjected to final rinse solutions which perform all of the conventional functions but which also consistently alleviate the noted problems.